CSL code, manual transmission and torque delivery maps

[ac427]

I believe the torque delivery maps in the CSL code should be adjusted if a different final drive ratio is used.

What effect do these maps have if the gearbox type is set manual transmission in the CSL code?

[karter16]

the torque delivery maps

To confirm - you're referring to KF_MD_MAX_MD_IND_OPT? any others? If you let me know I'll go through what I've got and see if it's good enough to understand what's going on.

[SliM3]

The main torque map is what's referenced when transmitting via CAN to SMG controller (if equipped) and the DSC controller. It's a bit crude compared to today's torque control strategies and only serves as a reference point for torque interventions. Playing with these values will naturally have an effect on the amount of tq cut and decay rate per event, at the target load. There are other torque maps that are active during closed loop idle control (friction torque model, accessory drive torque, etc.) which all work in conjunction with the ignition efficiency models.

What exactly is your goal? If you just want to avoid ASC kicking in whenever there’s the slightest amount of wheel slip, then that’s just a matter of changing the threshold scalar. Otherwise to really tweak the main tq map, I’d imagine you’d want to log & compare front/rear wheel speeds, slip, steering angle (maybe), etc.


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[ac427]

To confirm - you're referring to KF_MD_MAX_MD_IND_OPT? any others? If you let me know I'll go through what I've got and see if it's good enough to understand what's going on.

Thanks Karter, I'm not sure. It all came about when Tom (NZ_M3) mentioned them in relation to a diff ratio change.

I was just wondering if those maps had any bearing on a manual transmission car. It's probably a wild goose chase and i wouldn't want waste your time on it.

[ac427]

The main torque map is what's referenced when transmitting via CAN to SMG controller (if equipped) and the DSC controller. It's a bit crude compared to today's torque control strategies and only serves as a reference point for torque interventions. Playing with these values will naturally have an effect on the amount of tq cut and decay rate per event, at the target load. There are other torque maps that are active during closed loop idle control (friction torque model, accessory drive torque, etc.) which all work in conjunction with the ignition efficiency models.

What exactly is your goal? If you just want to avoid ASC kicking in whenever there’s the slightest amount of wheel slip, then that’s just a matter of changing the threshold scalar. Otherwise to really tweak the main tq map, I’d imagine you’d want to log & compare front/rear wheel speeds, slip, steering angle (maybe), etc.


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Thanks Brian. It was only to understand if i needed to adjust anything in my CSL tune to accommodate my 4.1 final drive with regard to the manual transmission.

Whereabouts is the scalar for ASC intervention?

[SliM3]

Thanks Brian. It was only to understand if i needed to adjust anything in my CSL tune to accommodate my 4.1 final drive with regard to the manual transmission.

Whereabouts is the scalar for ASC intervention?

Minimum TQ to enable ASC intervention. It's set to 00 so it's always active. I had mine set somewhere around 203 Nm (150 ft lbs).
K_MD_ASC_BEGR
0x9626 (2 bytes)
Convert: (x/10) = Nm



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[karter16]

Thanks Karter, I'm not sure. It all came about when Tom (NZ_M3) mentioned them in relation to a diff ratio change.

I was just wondering if those maps had any bearing on a manual transmission car. It's probably a wild goose chase and i wouldn't want waste your time on it.

Okay so having a look at the torque interventions function of the moment manager, there are some differences in how the torque interventions are calculated depending on whether the gearbox is SMG or manual (which we would expect), however the main maps apply regardless, and the CSL software appears to retain the appropriate code from the standard M3 software for the manual gearbox scenario. e.g. from what I can see the 0401 programme will handle torque delivery for a manual in the same way the regular M3 software does (which makes sense given we know in practice manual cars can run 0401 just fine).

As far as I can see gearbox type therefore has no impact on how the torque delivery maps are used.